This section is intended to introduce the reader to various aspects of art which may be related to various aspects of the present invention which are described and/or claimed below. This discussion is believed to be helpful in providing the reader with background information to facilitate a better understanding of the various aspects of the present invention. Accordingly, it should be understood that these statements are to be read in this light, and not as admissions of prior art.
A wireless LAN (WLAN) is a flexible data communications system implemented as an alternative or extension to a wired LAN within a building or campus. Using electromagnetic waves, WLANs transmit and receive data over the air, minimizing the need for wired connections. Thus, WLANs combine data connectivity with user mobility, and, through simplified configuration, enable movable LANs. Some industries that have benefited from the productivity gains of using portable terminals (e.g., notebook computers) to transmit and receive real-time information are the digital home networking, health-care, retail, manufacturing, and warehousing industries.
Manufacturers of WLANs have a range of transmission technologies to choose from when designing a WLAN. Some exemplary technologies are multicarrier systems, spread spectrum systems, narrowband systems, and infrared systems. Although each system has its own benefits and detriments, one particular type of multicarrier transmission system, orthogonal frequency division multiplexing (OFDM), has proven to be exceptionally useful for WLAN communications.
OFDM is a robust technique for efficiently transmitting data over a channel. The technique uses a plurality of sub-carrier frequencies (sub-carriers) within a channel bandwidth to transmit data. These sub-carriers are arranged for optimal bandwidth efficiency compared to conventional frequency division multiplexing (FDM) which can waste portions of the channel bandwidth in order to separate and isolate the sub-carrier frequency spectra and thereby avoid inter-carrier interference (ICI). By contrast, although the frequency spectra of OFDM sub-carriers overlap significantly within the OFDM channel bandwidth, OFDM nonetheless allows resolution and recovery of the information that has been modulated onto each sub-carrier.
The transmission of data through a channel via OFDM signals also provides several other advantages over more conventional transmission techniques. Some of these advantages are a tolerance to multipath delay spread and frequency selective fading, efficient spectrum usage, simplified sub-channel equalization, and good interference properties.
Processing OFDM signals requires the manipulation of very large quantities of data. Many functional blocks in typical OFDM receivers require the use of data buffers, which are memory locations that store data for subsequent processing. One exemplary functional block that uses a buffer in OFDM signal processing is the Fast Fourier Transform (FFT) module of a typical OFDM receiver. The FFT module may need a buffer to store incoming data as well as a temporary storage location while the basic computational units of the FFT (known as butterflies) compute the various stages. Another exemplary functional block that uses a buffer in OFDM signal processing is the equalizer module of a typical OFDM receiver. The equalizer module may need a buffer to store the data during the filtering and adaptation process.
The functional blocks or modules of OFDM receivers are typically connected in series so that the output of one functional block goes into a buffer associated with the next functional block. This arrangement takes up space and increases the processing overhead associated with processing OFDM signals. A buffer architecture that avoids these shortcomings would be desirable.